4kg: Prototype

Exclusive to the Chrome Web Store, 4kg: Prototype is a demo/beta for 4kg, an upcoming retro-2D platformer complete with pixel art and chiptune music.
This is the first game I've ever made and I've put a lot of hard work into its design, coding, and art. Give it a shot, and please rate and comment. If you really like it, then please consider using the "Support with Google Checkout™" option on the main menu. =)
Official Site: http://4kg.co
Dev Blog: http://gamesbyandrex.tumblr.com
Features:
- 4kg's first three levels!
- Pick-up-and-play controls mimicking the Super Mario series -- a button to run, a button to jump, and four keys for direction are all there are. There's also easy controls for sliding down walls and wall jumping.
- Ridiculously wicked-awesome retro chiptune music by a variety of artists including HeLL-Obit and Sup3r N3rd. Features three tracks out of the final game's nine.
- All of this free of charge! Well, it is a demo/beta. But the final game will be free too. (And open source!)
Tech:
- The HTML5 <canvas> and <audio> elements, not Adobe Flash. Runs well even on netbooks.
- Also uses HTML5 localStorage for game saves.
- As a packaged app, it can even be played completely offline!
Updates:
- November 15: Not an update for the game, but it seems Chrome's fixed the bugs related to the poor performance. Yay!
- 1.1.0, August 4: Much better fullscreen code that preserves aspect ratio. To try it, press "F." Note that unless you have an extremely good computer or are using beta/dev/Canary, it will run pretty slow.
- 1.0.2, May 31: Changed instances of Donate to Support to better comply with Google Checkout's guidelines.
- 1.0.1, May 31: Killing enemies should now be a lot easier. Still not perfect, but there shouldn't be any more cheap deaths.
Known Issues:
- You must hold the down key for a full second in order to pass through the dotted line platforms. Also, there is a bit of inaccuracy with the collision detection when passing up through them.
- It is possible to pass through the bounds of each level if you're going fast enough. If this happens, you'll have to reload the game.